I found this small, yet very important detail on a DB-37 connector attached to the back of a Nautel V-1 transmitter:

DB-37 connector for Nautel V-1 transmitter
DB-37 connector for Nautel V-1 transmitter

The black wire is the ground wire and the orange wire is the remote RF off command.  A closer view:

DB 37 connector from Nautel V-1 transmitter
DB 37 connector from Nautel V-1 transmitter

The transmitter had been shutting down unexpectedly since it was installed.  When these shutdowns occurred, there was no overload, no fault, no power interruption or other indication of a problem.  When the RF on command was issued, the transmitter would turn back on and run with normal readings until it shut down again.  It was a bit of a mystery; the transmitter was removed from its mountain top home and hauled back to the shop to be repaired.  It was connected to all sorts of test equipment and studied intently for many days.  Still, the problem could not be replicated in the shop.

Then the transmitter was hauled back to its mountain top transmitter site and re-installed.  It ran well for about a month and then started going off again.  This time somebody looked at the event log and noticed that a “Remote RF off command” was being issued at the same time the transmitter would shut down.  Ahhh, the missing bit of critical data.  That prompted me to take apart the DB-37 connector used for the remote control interface.  The problem was obvious as soon as I removed the hood.

Sometimes the most valuable piece of test gear is the venerable Mk I, Mod 0, EYEBALL.

I unsoldered the ground lead and put some heat shrink over the connection to the DB-37.  Hopefully, that will take care of it.

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3 thoughts on “Details”

  1. Not being familiar with Nautel stuff, was this the remote control connector that the user attached wires to, which was then plugged into the transmitter, or was this some internal connector wired up by Nautel? I wouldn’t expect an exposed wire on a DB-style connector to be an issue unless the wires were being moved or flexed all the time. From the photo, it seems there’s plenty of clearance between the black wire and its neighbor. Or had the wire been moved by the time you took the photo?

    Bob M.

  2. Bob, That is the customer side wiring, e.g. not internal to the transmitters. What is not immediately clear from the picture is that the db-37 hood forced the wires together. I should have taken the picture of the wires before I removed the other half of the hood, but is was one of those “Ah Ha!” moments.

  3. The best troubleshooting devices known to man, eyeballs and mind, 1.0. The original and best. What you can see or hear or not can point the way.

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